html,body,main{
    height: 100%;
    margin: 0;
}

main{
    display: flex;
    flex-direction: column;
}

.top,.left-nav,.look-page,.bottom{
    border: 1px solid #ccc;
    margin: 2px;

}

.top{
    height: 100px;
}

.main{
    flex-grow: 1;
    display:flex;
    flex-direction: row;
}

.left-nav{
    width: 200px;
}

.look-page{
    flex-grow: 1;

}

.bottom{
    height: 30px;
}